Naughty Naughty
From Halopedia, the Halo wiki
Naughty Naughty is an Achievement in Halo 3: ODST. It is awarded for killing 10 Engineers in New Mombasa at night, alone or with another ODST. It is worth 5 Gamerpoints.[1]
In contrast to the Good Samaritan achievement, it is represented by a downward facing ODST helmet lighted below by a red light.
If you stumble upon a group of Covenant being shielded by an Engineer and do not wish to give away your position by trying to kill the Engineer first, you may kill the squad they are shielding and they will self-destruct. As long as you have hit the Engineer with your weapon sometime during your attack, you will get credit for killing them. Mind you, this is extremely inefficient, as the Covenant soldiers you'll be fighting will all have enhanced shields, making them much more difficult to deal with than if you'd taken out the Engineer first.
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